Commit Graph

24 Commits

Author SHA1 Message Date
Ben Segall
f9f9ffc237 sched: Avoid throttle_cfs_rq() racing with period_timer stopping
throttle_cfs_rq() doesn't check to make sure that period_timer is running,
and while update_curr/assign_cfs_runtime does, a concurrently running
period_timer on another cpu could cancel itself between this cpu's
update_curr and throttle_cfs_rq(). If there are no other cfs_rqs running
in the tg to restart the timer, this causes the cfs_rq to be stranded
forever.

Fix this by calling __start_cfs_bandwidth() in throttle if the timer is
inactive.

(Also add some sched_debug lines for cfs_bandwidth.)

Tested: make a run/sleep task in a cgroup, loop switching the cgroup
between 1ms/100ms quota and unlimited, checking for timer_active=0 and
throttled=1 as a failure. With the throttle_cfs_rq() change commented out
this fails, with the full patch it passes.

Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/20131016181632.22647.84174.stgit@sword-of-the-dawn.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-29 12:02:32 +01:00
Ingo Molnar
b32e86b430 sched/numa: Add debugging
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1381141781-10992-53-git-send-email-mgorman@suse.de
2013-10-09 14:48:04 +02:00
Peter Zijlstra
fc840914e9 sched/debug: Take PID namespace into account
Emmanuel reported that /proc/sched_debug didn't report the right PIDs
when using namespaces, cure this.

Reported-by: Emmanuel Deloget <emmanuel.deloget@efixo.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130909110141.GM31370@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-12 19:14:16 +02:00
Alex Shi
333bb864f1 sched/debug: Remove CONFIG_FAIR_GROUP_SCHED mask
Now that we are using runnable load avg in sched balance, we don't
need to keep it under CONFIG_FAIR_GROUP_SCHED.

Also align the code style to #ifdef instead of #if defined() and
reorder the tg output info.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Cc: pjt@google.com
Cc: kamalesh@linux.vnet.ibm.com
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1372417835-4698-1-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-06-28 13:17:17 +02:00
Kamalesh Babulal
add332a152 sched/debug: Fix formatting of /proc/<PID>/sched
This patch alters format string's width, to align all statistics
at par with the longest struct sched_statistic member name under
/proc/<PID>/sched.

Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/20130627165005.GA15583@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-06-28 11:13:35 +02:00
Kamalesh Babulal
939fd731eb sched/debug: Add load-tracking statistics to task
At present we print per-entity load-tracking statistics for
cfs_rq of cgroups/runqueues. Given that per task statistics
is maintained, it can be used to know the contribution made
by the task to its parenting cfs_rq level.

This patch adds per-task load-tracking statistics to /proc/<PID>/sched.

Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130625080336.GA20175@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-06-27 10:07:46 +02:00
Alex Shi
bf5b986ed4 sched/tg: Use 'unsigned long' for load variable in task group
Since tg->load_avg is smaller than tg->load_weight, we don't need a
atomic64_t variable for load_avg in 32 bit machine.
The same reason for cfs_rq->tg_load_contrib.

The atomic_long_t/unsigned long variable type are more efficient and
convenience for them.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1371694737-29336-11-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-06-27 10:07:40 +02:00
Alex Shi
72a4cf20cb sched: Change cfs_rq load avg to unsigned long
Since the 'u64 runnable_load_avg, blocked_load_avg' in cfs_rq struct are
smaller than 'unsigned long' cfs_rq->load.weight. We don't need u64
vaiables to describe them. unsigned long is more efficient and convenience.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Reviewed-by: Paul Turner <pjt@google.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1371694737-29336-10-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-06-27 10:07:38 +02:00
Linus Torvalds
dcad0fceae Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar.

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cputime: Use local_clock() for full dynticks cputime accounting
  cputime: Constify timeval_to_cputime(timeval) argument
  sched: Move RR_TIMESLICE from sysctl.h to rt.h
  sched: Fix /proc/sched_debug failure on very very large systems
  sched: Fix /proc/sched_stat failure on very very large systems
  sched/core: Remove the obsolete and unused nr_uninterruptible() function
2013-02-26 19:42:08 -08:00
Nathan Zimmer
bbbfeac92b sched: Fix /proc/sched_debug failure on very very large systems
On systems with 4096 cores attemping to read /proc/sched_debug
fails because we are trying to push all the data into a single
kmalloc buffer.

The issue is on these very large machines all the data will not
fit in 4mb.

A better solution is to not us the single_open mechanism but to
provide our own seq_operations and treat each cpu as an
individual record.

The output should be identical to the previous version.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>)
[ Whitespace fixlet]
[ Fix spello in comment]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-02-22 10:27:25 +01:00
Linus Torvalds
502b24c23b Merge branch 'for-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup changes from Tejun Heo:
 "Nothing too drastic.

   - Removal of synchronize_rcu() from userland visible paths.

   - Various fixes and cleanups from Li.

   - cgroup_rightmost_descendant() added which will be used by cpuset
     changes (it will be a separate pull request)."

* 'for-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: fail if monitored file and event_control are in different cgroup
  cgroup: fix cgroup_rmdir() vs close(eventfd) race
  cpuset: fix cpuset_print_task_mems_allowed() vs rename() race
  cgroup: fix exit() vs rmdir() race
  cgroup: remove bogus comments in cgroup_diput()
  cgroup: remove synchronize_rcu() from cgroup_diput()
  cgroup: remove duplicate RCU free on struct cgroup
  sched: remove redundant NULL cgroup check in task_group_path()
  sched: split out css_online/css_offline from tg creation/destruction
  cgroup: initialize cgrp->dentry before css_alloc()
  cgroup: remove a NULL check in cgroup_exit()
  cgroup: fix bogus kernel warnings when cgroup_create() failed
  cgroup: remove synchronize_rcu() from rebind_subsystems()
  cgroup: remove synchronize_rcu() from cgroup_attach_{task|proc}()
  cgroup: use new hashtable implementation
  cgroups: fix cgroup_event_listener error handling
  cgroups: move cgroup_event_listener.c to tools/cgroup
  cgroup: implement cgroup_rightmost_descendant()
  cgroup: remove unused dummy cgroup_fork_callbacks()
2013-02-20 09:16:21 -08:00
Arnd Bergmann
cff3c124a7 sched/debug: Fix format string for 32-bit platforms
The type returned from atomic64_t can be either unsigned
long or unsigned long long, depending on the architecture.
Using a cast to unsigned long long lets us use the same
format string for all architectures.

Without this patch, building with scheduler debugging
enabled results in:

  kernel/sched/debug.c: In function 'print_cfs_rq':
  kernel/sched/debug.c:225:2: warning: format '%ld' expects argument of type 'long int', but argument 4 has type 'long long int' [-Wformat]
  kernel/sched/debug.c:225:2: warning: format '%ld' expects argument of type 'long int', but argument 3 has type 'long long int' [-Wformat]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: linux-arm-kernel@list.infradead.org
Link: http://lkml.kernel.org/r/1359123276-15833-7-git-send-email-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-01-25 15:23:15 +01:00
Li Zefan
2a73991b76 sched: remove redundant NULL cgroup check in task_group_path()
A task_group won't be online (thus no one can see it) until
cpu_cgroup_css_online(), and at that time tg->css.cgroup has
been initialized, so this NULL check is redundant.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2013-01-24 12:05:18 -08:00
Paul Turner
82958366cf sched: Replace update_shares weight distribution with per-entity computation
Now that the machinery in place is in place to compute contributed load in a
bottom up fashion; replace the shares distribution code within update_shares()
accordingly.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141507.061208672@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 10:27:28 +02:00
Paul Turner
bb17f65571 sched: Normalize tg load contributions against runnable time
Entities of equal weight should receive equitable distribution of cpu time.
This is challenging in the case of a task_group's shares as execution may be
occurring on multiple cpus simultaneously.

To handle this we divide up the shares into weights proportionate with the load
on each cfs_rq.  This does not however, account for the fact that the sum of
the parts may be less than one cpu and so we need to normalize:
  load(tg) = min(runnable_avg(tg), 1) * tg->shares
Where runnable_avg is the aggregate time in which the task_group had runnable
children.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.930124292@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 10:27:26 +02:00
Paul Turner
c566e8e9e4 sched: Aggregate total task_group load
Maintain a global running sum of the average load seen on each cfs_rq belonging
to each task group so that it may be used in calculating an appropriate
shares:weight distribution.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.792901086@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 10:27:24 +02:00
Paul Turner
9ee474f556 sched: Maintain the load contribution of blocked entities
We are currently maintaining:

  runnable_load(cfs_rq) = \Sum task_load(t)

For all running children t of cfs_rq.  While this can be naturally updated for
tasks in a runnable state (as they are scheduled); this does not account for
the load contributed by blocked task entities.

This can be solved by introducing a separate accounting for blocked load:

  blocked_load(cfs_rq) = \Sum runnable(b) * weight(b)

Obviously we do not want to iterate over all blocked entities to account for
their decay, we instead observe that:

  runnable_load(t) = \Sum p_i*y^i

and that to account for an additional idle period we only need to compute:

  y*runnable_load(t).

This means that we can compute all blocked entities at once by evaluating:

  blocked_load(cfs_rq)` = y * blocked_load(cfs_rq)

Finally we maintain a decay counter so that when a sleeping entity re-awakens
we can determine how much of its load should be removed from the blocked sum.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.585389902@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 10:27:22 +02:00
Paul Turner
2dac754e10 sched: Aggregate load contributed by task entities on parenting cfs_rq
For a given task t, we can compute its contribution to load as:

  task_load(t) = runnable_avg(t) * weight(t)

On a parenting cfs_rq we can then aggregate:

  runnable_load(cfs_rq) = \Sum task_load(t), for all runnable children t

Maintain this bottom up, with task entities adding their contributed load to
the parenting cfs_rq sum.  When a task entity's load changes we add the same
delta to the maintained sum.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.514678907@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 10:27:21 +02:00
Ben Segall
18bf2805d9 sched: Maintain per-rq runnable averages
Since runqueues do not have a corresponding sched_entity we instead embed a
sched_avg structure directly.

Signed-off-by: Ben Segall <bsegall@google.com>
Reviewed-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.442637130@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 10:27:20 +02:00
Paul Turner
9d85f21c94 sched: Track the runnable average on a per-task entity basis
Instead of tracking averaging the load parented by a cfs_rq, we can track
entity load directly. With the load for a given cfs_rq then being the sum
of its children.

To do this we represent the historical contribution to runnable average
within each trailing 1024us of execution as the coefficients of a
geometric series.

We can express this for a given task t as:

  runnable_sum(t) = \Sum u_i * y^i, runnable_avg_period(t) = \Sum 1024 * y^i
  load(t) = weight_t * runnable_sum(t) / runnable_avg_period(t)

Where: u_i is the usage in the last i`th 1024us period (approximately 1ms)
~ms and y is chosen such that y^k = 1/2.  We currently choose k to be 32 which
roughly translates to about a sched period.

Signed-off-by: Paul Turner <pjt@google.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.372695337@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 10:27:18 +02:00
Peter Zijlstra
13e099d2f7 sched/debug: Fix printing large integers on 32-bit platforms
Some numbers like nr_running and nr_uninterruptible are fundamentally
unsigned since its impossible to have a negative amount of tasks, yet
we still print them as signed to easily recognise the underflow
condition.

rq->nr_uninterruptible has 'special' accounting and can in fact very
easily become negative on a per-cpu basis.

It was noted that since the P() macro assumes things are long long and
the promotion of unsigned 'int/long' to long long on 32bit doesn't
sign extend we print silly large numbers instead of the easier to read
signed numbers.

Therefore extend the P() macro to not require the sign extention.

Reported-by: Diwakar Tundlam <dtundlam@nvidia.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-gk5tm8t2n4ix2vkpns42uqqp@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-05-14 15:05:28 +02:00
Peter Zijlstra
c82513e513 sched: Change rq->nr_running to unsigned int
Since there's a PID space limit of 30bits (see
futex.h:FUTEX_TID_MASK) and allocating that many tasks (assuming a
lower bound of 2 pages per task) would still take 8T of memory it
seems reasonable to say that unsigned int is sufficient for
rq->nr_running.

When we do get anywhere near that amount of tasks I suspect other
things would go funny, load-balancer load computations would really
need to be hoisted to 128bit etc.

So save a few bytes and convert rq->nr_running and friends to
unsigned int.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-y3tvyszjdmbibade5bw8zl81@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-05-09 15:00:49 +02:00
Rakib Mullick
30fd049afc sched: Remove sched_switch
Currently we don't utilize the sched_switch field anymore.

But, simply removing sched_switch field from the middle of the
sched_stat output will break tools.

So, to stay compatible we hardcode it to zero and remove the
field from the scheduler data structures.

Update the schedstat documentation accordingly.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1327422836.27181.5.camel@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-01-27 13:28:53 +01:00
Peter Zijlstra
391e43da79 sched: Move all scheduler bits into kernel/sched/
There's too many sched*.[ch] files in kernel/, give them their own
directory.

(No code changed, other than Makefile glue added.)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-17 12:20:22 +01:00